Imaging Findings of Adenocarcinoma Arising from Lingual Foregut Duplication Cyst

Lingual foregut duplication cysts are rare developmental anomalies with varied symptoms, and adenocarcinomas may develop from them. Radiological evaluations, including computed tomography and magnetic resonance imaging, can help diagnose these lesions and determine their extent. Abnormal enhancement should raise the suspicion of malignancy of a lingual foregut duplication cyst. Early detection and complete surgical resection of lingual foregut duplication cysts are necessary to prevent malignant transformations. Complete tumor resection with adjuvant radiotherapy or radiochemotherapy is recommended. The teaching point is that mucinous adenocarcinoma can develop from a lingual foregut duplication cyst, and radiological studies may aid in the diagnosis. Teaching Point: Adenocarcinomas can develop from lingual foregut duplication cysts, which are rare developmental anomalies, and radiologic studies may aid in the diagnosis.


SUNG-EUN CHOI
*Author affiliations can be found in the back matter of this article Imaging Findings of Adenocarcinoma Arising from Lingual Foregut Duplication Cyst

INTRODUCTION
Congenital cystic lesions with foregut-derived epithelial linings, known as foregut duplication cysts, can manifest anywhere from the oral cavity to the anus [1]. Lingual foregut duplication cysts are rare and account for only 0.3% of all diagnosed foregut cysts [2]. Adenocarcinomas rarely develop from lingual foregut duplication cysts, and reports on their radiologic findings are limited.

CASE HISTORY
A 63-year-old male presented to the outpatient clinic of the otorhinolaryngology department with complaints of the sensation of mouth fullness and dysphagia that had lasted for three months. On physical examination, the tongue showed bulging contour with a normal overlying mucosa.
Enhanced neck computed tomography (CT) and magnetic resonance imaging (MRI) revealed a wellcircumscribed lobulated cystic mass in the tongue, measuring approximately 6.7 × 5.7 × 5.1 cm. CT images showed a low-attenuation mass with multifocal internal calcifications, and septa-like structures were observed within the mass (Figure 1). On neck MRI, the mass was hyperintense on T2-weighted imaging (T2WI) and isointense on T1-weighted imaging (T1WI) with thin enhancing internal multiseptations ( Figure 2). There was no evidence of pathological lymph node in the neck. The initial radiologic diagnosis of this mass was a lingual foregut duplication cyst, with differential diagnoses of lymphatic malformation and dermoid cyst. Given the impression of a benign mass, the surgeon proceeded with trans-oral resection surgery. After histopathological analysis of the excised mass, the final diagnosis was mucinous adenocarcinoma (Figure 3), and tumor involvement at the resection margin was positive.
The patient underwent positron emission tomography/CT scan to exclude the possibility of a metastatic lesion from a primary intestinal malignancy, and there was no evidence of a metabolically active lesion in any location other than the resection margin of the tongue (Figure 4). Upper endoscopy and colonoscopy were performed; however, no abnormal findings were observed.
After a multidisciplinary discussion, total glossectomy was planned as a treatment plan, and adjuvant radiochemotherapy was considered a subsequent treatment regimen.

COMMENTS
Lingual foregut duplication cysts are uncommon anomalies that occur as a result of remnant heterotopic rests of the foregut-derived epithelium after the first  trimester of embryological development [1]. Although exceedingly rare, adenocarcinomas can develop from foregut duplication cysts and have mostly been reported in alimentary organs [3,4]. There have been reported cases of primary intestinal-type adenocarcinoma developing on the tongue; however, most are believed to originate from minor salivary gland tissues [5,6]. To the best of our knowledge, this is the second reported case of adenocarcinoma arising from a lingual foregut duplication cyst [7]. Therefore, this report may provide evidence that emphasizes the need for early detection and resection of lingual foregut duplication cysts to prevent malignant transformation.
Radiologic evaluations can help diagnose these lesions and determine their extent. In our case, enhancements of the peripheral wall and internal septations of the lingual foregut duplication cyst were observed on radiologic images, and these imaging findings may reflect the malignant transformation of foregut duplication cyst.
Although no standardized treatment protocol has been established for adenocarcinomas arising from foregut duplication cysts because of their rarity, complete resection with adjuvant radiotherapy or radiochemotherapy is recommended [5].